(a) Field of the Invention
This invention relates to carburetors for internal combustion engines and more particularly to improvements in a carburetor of a type provided with a butterfly-shaped throttle valve.
(b) Description of the Prior Art
FIG. 1 shows a basic structure of a carburetor of a type provided with a known butterfly-shaped throttle valve used mostly for internal combustion engines for general purposes. In the drawing, reference numeral 1 indicates a carburetor body, 2 indicates a venturi portion, 3 indicates a butterfly-shaped throttle valve, 4 indicates a main nozzle, 5 indicates a main jet, 6 indicates a main air jet, 7 indicates a pilot jet, 8 indicates a pilot air jet, 9 indicates a low speed fuel passage, 10 indicates an idling screw, 11 indicates a float, 12 indicates a cover case for defining a float chamber, 13 indicates a screw for attaching the cover case 12 to the carburetor body 1 and 1A indicates a boss portion hanging into the float chamber. As this kind of carburetor is arranged as described above, for example, in case the main jet 5 is to be removed from the boss portion 1A so as to be replaced, first the cover case 12 will have to be removed from the carburetor body 1. As a result, when the carburetor is attached to an engine, a very difficult work will be forced. Further, as the boss portion 1A occupies a comparatively large volume part within the float chamber, the effective volume of the float chamber will reduce and therefore the float chamber will have to be comparatively large as a whole. As the float 11 must also be made to be in such form as will not contact the boss portion 1A, there has been a disadvantage that the structure is limited. The same problem as in the case of the main jet 5 will occur also in the case of replacing the pilot jet 7.